> It's determined by the value of the property around it, and that property in aggregate is determined by the wealth of the jobs congregated there, and the concentration of capital located there.

The value of something is set by what people are willing to pay for it. I.e. supply and demand.

> Despite this, units cost has increased by about 700% during that time.

Average inflation since 1970 is 565%. 700% is within that, as inflation measurements are inexact and there are regional differences as well.